This invention relates to the joining of sheets or panels formed of wood, wood particles or wood fibres (hereafter referred to as panels). Such panels are manufactured in various sizes, the most common in use in Australia measures 5.5.times.1.4 meters. Such panels are extensively used in the building and manufacturing industry and when so used such panels have to be frequently cut to a particular size and in consequence there is, in many cases, considerable wastage of material because of such off-cuts.